Railway traffic controlling apparatus



May 17, 1932. NETTLETON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed April 1'7, 1928 2 Sheets-Sheet l f I] I6 [5 14 4 G 72 2 f. 1' W T 5 r T A I? -3 4 5 f is 12 $57 8 z a I1 [1c 11 [I I6, 5 FZyZ. D- 6 4 0 ;2 -5. 2

26 [my a 4 2 6 INVENTORI ,L, LJVCtt/eZa May 17, 1932. L. NEI 'TLETON 1,858,901

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed April 17, 1928 2 Sheets$heet 2 INVENTOR'. A .A Matt/eta n,

Patented May 17, 1932 STES LEWIS L. NETTLETON, OF EDGEWOOD' BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF TION 01E PENNSYLVANIA SWISSVALE, PENNSYLVANIA, A CORPORA- RAILWAY TRAFFIC CON TROLLING- APPARATUS Application filed April 17,

My invention relates to railway traflic controlling apparatus, and particularly to apparatus of the type wherein periodically varying alternating current is supplied to the track rails for the control of trains.

I will describe several forms of railway trafiic controlling apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view illustrating one form of railway traffic controlling apparatus embodying my invention. Figs. 2, 3, 4, and 5 are similar views showing modified forms of the apparatus illustrated in Fig. 1, and also embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, the reference characters 1 and 1 designate the track rails of a stretch of railway track over which traffic normally moves in the direction indicated by the arrow. These rails are divided, by means of insulated joints 2, to form a plurality of successive track sections, only one of which, A-B, is shown complete in the drawings. Train controlling current is supplied to the track rails of section A B by means of a transformer T, the secondary 3 of which is connected across the track rails adjacent the exit end of the section. The primary 4': of transformer T is at times supplied with alternating current from a suitable source, here shown as the secondary 5 of a transformer D, the primary 6 of which in constantly supplied with alternating current from an alternator G. The frequency of this current may be of the order of the usual commercial alternating current such as 60 cycles or 100 cycles per second.

The reference character R designates a polarized relay, provided with a winding 12 and a contact member 11. When current of one relative polarity flows through the winding 12, the contact member 11 moves to the left-hand or reverse position to close contacts 1111 and 11-11, and when current of opposite relative polarity flows through the winding 12, the contact member 11 moves to the right-hand or normal position to close contact 11-11. The winding 12 of relay R is connected in series with the secondary 9 of a transformer E, an inductance L, and a condenser 0 toform a resonant circuit, which is designated in general by the reference character W The inductance L and the condenser C may have any reasonable values, but for purposes of explanation, I will assume that the natural period of the circuit is 180 cycles per minute. A condenser C may be connected in parallel with the condenser C by closing switch S Likewise, another condenser C may be connected in parallel with the condenser C by closing switch S When switch S is closed the natural period of the circuit including relay R is 120 cycles per minute, and when both switches S and S are closed the natural period of the circuit including the relay is 80 cycles per minute. The switches S and S may be controlled in accordance with trafiic conditions by means which form no part of my present invention, and which are therefore omitted from the drawings.

The primary 13 of transformer E is supplied with direct current from a suitable source of energy such as a battery F over contacts of relay B. When relay R is in the reverse position, in which it is shown in the drawings, current flows from battery F through the right-hand half of primary 13 of transformer E in one direction, thence through wire H, contact 1111 and wires 16 and 15 back to the battery F. When relay R is in the normal position, current flows from the battery F through the left-hand half of primary 13 of transformer E in the opposite direction, thence through wire 17,

Serial No. 270,680.

contact 11-11% and wires 16 and 15 back to' the battery F. i

In explaining the operation of the apparatus, I will assume that switches S and S are open, and that relay R has just been energized in the reverse direction so that contact 11-11 is closed. A surge of current is then supplied to the right-hand half of primary 13, and during the growth of this current to its steady value, an electromotive force is induced in the secondary 9 of transformer E. This induced electromotive force excites the resonant circuit so that the circuit oscillates at its natural period of 180 cycles per minute. The parts are so arranged that during the first charge of condenser C the current in the resonant circuit W flows in such direction that contact 1111 is held closed. When the condenser C next discharges due to free oscillations set up in the resonant circuit V7 the current in the circuit flows, of course, in the opposite direction, so that relay B- becomes energized in the normal direction to open contact 111l and to close contact ll-il. Upon opening contact 1l11b, the current decays in the right-hand half of p-imary l3, and upon closing contact 1111 t is current rises to a steady value in the left-hand half of primary 13. The decay of current in the one half of the primary 13 and the rise of current in the other half unite to induce another electromotive force in the secondary 9 of transformer E, and the resultant current which flows in the resonant circuit again charges condenser C Since this resultant current is of the same relative polarity a that which operated relay R to close conta 1111, the contact 1111 remains closed. lVhen condenser C next discharges, how" ever, the relay 1% is energized in the reverse direction to open contact 11-11 and to again close contact 11-ll The current thereupon decays in the left-handhalf of primary 13, and rises to its steady value in the right-hand half of primary 13; and it follows that an electromotive force again induced in the secondary 9, of transformer E. The cycle of operations just described is then repeated, the relay R operating to swing its contact member al ernately to one extreme position and the other.

It is apparent from the foregoing discussion that condenser C is alternately charged and discharged, and that the relative polarity of the plates is reversed for successive charges. It is also apparent that for one complete cycle of the resonant circuit, that is, for two successive charges and discharges of condenser C relay R makes one complete operation from one extreme position to the other and back to the original position. It follows, that relay R operates at the frequency to which the resonant circuit is tuned, which in this instance is 180 cycles per minute. If now, condenser C is connected in parallel with condenser C to change the natural period of the circuit to 120 cycles per minute, the operation of the apparatus will be the same as before, but relay R will now operate at 120 cycles per minute. Likewise, if condensers C and C are both con nected in parallel with condenser C to change the natural period of the resonant circuit to cycles per minute, relay i..- will operate at 80 cycles per minute. By varying the natural period of the resonant circuit through rectifier H.

including the relay, therefore, the period of operation of relay B may be varied, and the relay can be made to operate at a frequency which depends on the natural period of the resonant circuit.

The supply of current to the primary 4': of transformer T, and hence to the track rails, is controlled over contact 1111 of relay R. Thus, when relay R is in the reverse position, current flows from the secondary 5 of transformer D through wire 10, thence through contact l111 wires 16 and 8, primary l of transformer T, and wire 7 back to the secondary 5 of transformer T. When the relay is in the normal position, contact 1111 is open, and the circuit just traced is interrupted. The contact 11-11 is closed once during each cycle of operation of relay It, and it follows that the track rails are supplied with current which is periodically varied at the natural frequency of the resonant circuit including the relay.

Referring now to 2, the apparatus shown in this View is the same as that shown in 1, except that inductance L is omitted from the resonant circuit which is here designated W This is made possible by d signing the secondary 9 of transformer E so that the total amount of inductance in the resonant circuit N is the same as the total amount of the inductance in the resonant circuit W In the modified form of apparatus shown in Fig. 3, a resonant circuit W is formed by connecting winding 12 of relay It in series with an auto-transformer J, and the three condensers C C and C The condenser C may he shunted by a switch S and another switch S is connected in parallel with the condenser C When switches S and S are both open, the natural period of the circuit including the relay is 180 cycles per minute. hen switch S is closed, the natural period of this circuit becomes 120 cycles per minute, and when switches S and S are both closed, the natural period of the circuit becomes 80 cycles per minute. Witl the condensers connected in the resonant circuit in this manner, it is impossible for the rails to receive current which is periodically varied at the wrong frequency due to an open circuit in one of the condensers, for should an open circuit occur, the resonant circuit would be interrupted, and relay B would cease to operate.

The energy for producing oscillation is suppli d from a secondary 18-of transformer D through a full wave rectifier H. W hen relay l3 is in the reverse position in which it is shown in the drawings, current flows from the secondary 18 of transformer 13 through the rectifier H, wire 23, section 28 of auto transformer J, wire 24, contact 1l1l of relay R, wire 25, and back to secondary 18 When relay R is in the normal position, current flows from the secondary 18 of transformer D through rectifier I-I wire 23, section 27 of auto-transformer J,

. wires 26 and 32, contact 11-11 of relay R,

2, and will be apparent from the drawings without describing it in detail.

Referring now to Fig. 4, relay R is controlled by a resonant circuit 7* in substantially the same manner that therelay is controlled by circuit W in Fig. 3, with the excepti on that in Fig. 4, the tuning is controlled by a switch having a movable member 33 arranged to selectively engage one of the fixed contacts 33*, 33 and 33. When contact 33-33 of switch K is closed, condenser C is included in the resonant circuit 7*, and the natural period of this circuit is 80 cycles per minute. hen contact 3333 of switch K is closed, condenser C is included in the circuit, and the natural period of the circuit is 120 cycles per minute. Similarly, when contact 33-33 is closed, condenser C is included in the circuit, and the natural period is 180 cycles per minute. With the condensers connected in this manner, if an open circuit or a short circuit occurs in the condenser which is included in the circuit, the resonance of the circuit is destroyed and relay R ceases to operate, so the rails cannot re- 7 ceive current which is periodically varied at J is provided the wrong frequency.

Referring now to Fig. 5, the apparatus here shown is similar to that illustrated in Fig.-

4:, except that in Fig. 5 the natural perlod of the resonant circuit, which is here designated W is varied by varying the inductance of the circuit instead of by varying the ca pacitance of the circuit as shown in Fig. 4. To accomplish this result, auto-transformer with taps 35, 36, and 37 which taps are connected respectively with the fixed contacts 33 33 and 33 of switch K. When contact 33-33 of switch K is closed, the resonant circuit W includes sections 27, 28, and 40 of auto-transformer J, and the parts are so proportioned that the natural period of the circuit is then 180 cycles per minute. WVhen contact 33-33 of switch K is closed, section 39 of auto-transformer J is connected in the resonant circuit in addition to sections 27, 28, and 40, and the natural period of the resonant circuit is then 120 cycles per minute. In similar manner, when contact 3333 of switch K is closed, sections 27, 28, 40, 39, and 38 of auto-transformer J are all included in the resonant circuit and the natural period of the circuit is then 80 cycles per minute. This form of apparatus only requires one condenser, and the apparatus is therefore less expensive to construct than the forms previously described. Furthermore, since only one condenser is used, if this condenser fails, the resonant circuit will stop oscillating, and the possibility of the rails being supplied with current which is varied at the wrong frequency is therefore small.

Apparatus embodyingmy invention is particularly suitable for, though in no way limited to, use in train control systems of the type comprising train carried governing means Which is selectively responsive to the frequency of variations in the current supplied to the trackway. It will be observed that in each of the forms of apparatus embodying my invention which are herein disclosed, the frequency of the variation in the trackway current is dependent upon the natural period of an electrical circuit. It is well known that the natural period of a-circuit of this type depends upon physical characteristics of elements which are comparatively permanent in nature so that after the apparatus has once been adjusted to varythe trackway current at a predetermined frequency, this adjustment will remain substan- V tially constant for a long period of time. In train control systems of the type described, this feature is extremely valuable since with a constant frequency of variation of the trackway current, there is little probability of improper operation of the train carried governing means.

Although I have herein shown and described only a few forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is 1. In combination, a stretch of railway track, a resonant circuit, means for varying the natural period of said circuit, and

means for supplying the rails of said stretch with alternating current which is modulated at a frequency which depends upon the natural period of said circuit. 7

2. In combination with a stretch of railway track, a source of alternating current connected with the rails of said stretch, an oscillating circuit, and means responsive to the instantaneous relative polarity of the current flowing in the oscillating circuit for modulating thealternating current supplied to the rails.

3. In combination, a stretch of railway track, a winding, a circuit including said winding, means for varying the. natural period of said circuit, means controlled by said Winding for producing oscillations in said circuit, means for supplying the rails of said stretch with train controlling current, and means controlled by said winding for periodically varying said train controlling current at a frequency which depends upon the natural period of said circuit.

4. In combination, a stretch of railway track, a winding, a circuit including the winding, means for varying the natural period of said circuit, means for supplying said stretch with train controlling current, and means controlled by said winding for periodically varying said train controlling current at the natural frequency of the resonant circuit.

5. In combination, a stretch of railway track, a resonant circuit, and means for supplying the rails of said stretch with alternating current which is modulated at the resonant frequency of said circuit.

6. In combination, a stretch of railway track, a winding, a transformer, a condenser; a resonant circuit including said winding, the secondary of said transformer, and said condenser in series, means controlled by said winding for at times supplying unidirectional current to. the primary of said transformer to produce oscillations in the resonant circuit, means for supplying the rails of said stretch with current, and means also controlled by said winding for periodically varying the current supplied to the track rails at a frequency which depends upon the natural period of the resonant circuit.

7. In combination, a stretch of railway track, a polarized relay, a resonant circuit including the winding of said relay, means for varying the natural period of said circuit, means for setting up oscillations in said circuit, a source of alternating current connected with the rails of said stretch, and means controlled by said relay for periodically varying the current supplied to the rails.

8. In combination, a stretch of railway track, a condenser, an inductance, a polarized relay; an oscillating circuit including the condenser, the inductance, and the winding of said relay; and means for supplying the rails of said stretch with current which is periodically varied at the frequency of operation of said relay.

9. In combination, a stretch of railway track, a condenser, an inductance, a relay havin its winding connected in series with the condenser and the inductance to form a resonant circuit and such relay responding to the periodic variations of the current flowing in its winding, and means controlled by the relay for supplying train controlling current to said stretch.

10. In combination with a stretch of railway track, a relay, a resonant circuit including the winding of said relay, means for producing oscillations in said circuit, and means cont-rolled by said relay for supplying the rails of said stretch with current.

11. In combination, a stretch of railway track, a winding, a transformer, a tuned circuit including said winding and the second ary of said transformer, a source of unidirectional current, means controlled by said winding for reversibly supplying current from said source to the primary of said transformer, means for supplying train controlling current to said stretch, and means controlled by said winding for periodically varying said train controlling current.

12. In combination, a stretch of railway track, an auto transformer, a plurality of condensers, a winding; a resonant circuit including said winding, said auto transformer, and all of the condensers connected in series; means for shunting one or more of said condensers to change the natural period of the resonant circuit; a rectifier, means controlled by said winding and including said rectifier for reversibly supplying unidirectional current to a portion of said auto transformer; means for supplying train controlling current to said stretch, and means also controlled by said winding for periodically varying said train controlling current.

13. In combination, a stretch of railway track, an auto transformer, a plurality of condensers, a winding; a resonant circuit including said winding, said auto transformer, and all of the condensers connected in series; means for shunting one or more of said condensers to change the natural period of the resonant circuit; a source of unidirectional current, means controlled by said winding for reversibly supplying current from said source to a portion of said auto transformer; means for supplyin train controlling current to said stretch, and means also controlled by said winding for periodically varying s id train controlling current.

14. In combination, a stretch of railway track. a resonant circuit, means for varying the impedance of said circuit to change the natural period of the circuit, and means for supplying the rails of said stretch with alternating current which is modulated at a fre quency which depends upon the natural period of said circuit.

15. In combination, a stretch of railway tracluan auto transformer, a resonant circuit including a selected portion of said auto transformer, and means for supplying the rails of said stretch with current which is periodically varied at a frequency which depends upon the natural period of said circuit.

16. In combination, a stretch of railway rack, an auto transformer, a condenser, a winding; a resonant circuit including said winding, said condenser. and a selected portion of said auto transformer; a source of unidirectional current, means controlled by said winding for reversibly supplying cur rent from. said source to a portion of said auto transformer, means for supplying train controlling current to said stretch, and means also controlled by said winding for periodically varying said train controlling current.

17. In combination, a stretch of railway track, a polarized relay, a resonant circuit including the winding of said relay, means controlled by said relay for exciting said resonant circuit to cause the relay to operate at a frequency which depends upon the natural period of said resonant circuit, and means for supplying the rails of said stretch with current which is periodically varied at the frequency of operation of said relay.

18. In combination, a stretch of railway track, a polarized relay, a resonant circuit including said relay, means controlled by said relay for exciting said circuit to cause the relay to operate at the natural frequency of said circuit, and means for supplying the rails of said stretch with current which is periodically varied at the frequency of operation of said relay.

19. In combination, a stretch of railway track, a polarized relay, a resonant circuit including said relay, means for varying the natural period of said circuit, means controlled by said relay for exciting said resonant circuit to cause the relay to operate at the natural frequency of said circuit, and means for supplying the rails of said stretch with current which is periodically varied at the frequency of operation of said relay.

20. In combination, a stretch of railway track, an inductance, a plurality of condensers, a winding, a transformer; a resonant circuit including the inductance, one of said condensers, the winding, and the secondary of said transformer; means for connecting one or more of the remaining condensers in parallel with said one condenser, a source of unidirectional current, means controlled by said winding for reversibly supplying current from said source to the primary of said transformer; means for supplying train controlling current to the rails of said stretch, and means also controlled by said winding for periodically varying said train controlling current.

21. In combination, a stretch of railway track, a plurality of condensers, a transformer, a winding; a resonant circuit including the winding, one of said condensers, and the secondary of said transformer; means for connecting one or more of the remaining condensers in parallel with said one condenser to change the natural period of the resonant circuit; a source of unidirectional current, means controlled by said winding for reversibly supplying current from said source to the primary of said transformer, means for supplying train controlling current to said stretch, and means controlled by said winding for periodically varying said train controlling current.

22. In combination, a stretch of railway track, an autotransformer tapped to form a plurality of sections, a polarized relay, a condenser connected in series with said relay and at least one section of said transformer to form a resonant circuit, a source of unidirectional current, means controlled by said relay for reversibly supplying current from said source to a portion of said autotransformer, means for at times connecting other sections of said autotransformer in said resonant circuit to change the natural period of the circuit, means for supplying train controlling current to said stretch, and means also controlled by said relay for periodically varying said train controlling current.

In testimony whereof I affix my signature.

LEWIS L. NETTLETON. 

